The invention relates to the improvement of a karaoke music reproduction device for the reproduction of music and lyrics by the selection of of a piece of music from a database containing a large number of pieces of music stored in binary coded form. The database can be stored either in a host computer memory unit from which data is downloaded as required via a public analog line or else a public digital line to an on-line terminal, or, in the case of an independent reproduction unit, the database can be stored on an external magneto-optical disc or similar device.
A karaoke musical reproduction device refers to an electric device which reproduces musical accompaniments for a song while at the same time displaying the lyrics of the song on a display device such as a visual display unit. The user is able to read the lyrics as they are displayed and to sing along through a microphone in time with the musical accompaniment.
Formerly, if a person, either in his own home or outside in a bar or restaurant, wished to have the pleasure of singing along to a karaoke backing while reading the lyrics of the required song from a visual display unit, then he would also need to have access to a reproduction unit and a selection of data media such as specially prerecorded tapes or video disc. Karaoke is, however, becoming extremely popular and each of the manufacturers involved in the business has at least 3,000 separate pieces of karaoke music on offer to the public. The considerable expense involved in building up a large collection and the storage space required may thus both present problems for the user. Furthermore, a user who wishes to keep abreast of all the new releases must resign himself to a very substantial monthly outlay. Users who do not currently face problems in terms of medium (prerecorded tape, video disc) storage space must also take account of the fact that such a fortunate situation will not necessarily last forever as their collections build up.
In order to meet this problem the applicants have invented a device whereby karaoke music is created in individual units (tune or piece of music), using the smallest possible amount of data, and then stored, along with other similarly created units, in a compact database. A terminal unit and a public communications line can be used to access any of the pieces of music selected from the said database. (See European Unscreened Patent No. 0372678 and U.S. Pat. application Ser. No. 07/372,029).
The fundamental concept on which the current invention is based involves the incorporation into the reproduction unit of an analog sound source or digital sound source conforming to the MIDI (Musical Instrument Digital Interface) international standard, and the configuration of data in the form of sequences of MIDI signals which are the digital signals used to drive the sound source. The selected data is then processed by the microprocessor and the MIDI signals transmitted via the sequencer to the sound source while the lyric related data transmitted via the lyric processing unit for display on the visual display unit. Thus, by using only the signals required to drive the sound as the data required for musical reproduction, it has been possible to restrict the volume of data required for the reproduction of any given piece of music.
The types of electronic musical instruments which are structured to enable the operation of a sound source conforming to the aforementioned MIDI standard by means of a keyboard, for example, commonly incorporate a mechanism to enable the reproduction of music on the basis of data stored on magnetic disc. There is no experience of time lag when reading data from a magnetic disc not only because the reading operation itself is relatively fast but also because there is no need for particularly large amounts of data in order to use a sound source as a musical instrument. However, in the case of a karaoke musical reproduction unit, the data that requires processing is a more complex mixture not only of the music data itself but also of lyric data and of music and lyric synchronization data. For this reason the use of a single main microprocessor to process all the required data raises problems in terms of the absolute capacity of microprocessor. The external memory unit which is used in conjunction with the terminal also needs to have a fairly large capacity which makes the use of the known magneto-optical disc technique seem most appropriate. Unfortunately, however, reading from a magneto-optical disc takes longer than reading from a normal magnetic disc. The process of reading data from a magneto-optical disc also requires the use of a dedicated unit for the amplification and serial-parallel conversion of the high-density bit stream emitted by the optical pick-up. Generally speaking the main microprocessor will also be programmed to correct errors in the parallel data blocks emanating from the said dedicated unit. In this case the read-out of data from the dedicated unit is given absolute priority. If, therefore, we assume for the moment that there is an overlap between the musical reproduction processing time and the time required for the loading of the dedicated unit, then the musical reproduction processing will be deferred. This will significantly increase the frequency with which musical reproduction processing is inhibited. If such inhibit periods begin to accumulate then accurate musical reproduction will eventually become impossible. If we are to exercise effective control over karaoke music reproduction time, then clearly we must find the answers to these problems.
Furthermore, for the purposes of the present invention, the applicants also envisage on-line connection of the reproduction unit to a host computer. Data would be downloaded from the host computer via a public communications line and subsequently processed by means of a known modem processing operation for input to the reproduction unit in serial data format. The terminal unit converts the said data into an "n"-bit data sequence for storage in main memory. If the data is stored in the main microprocessor in fixed quantities, then a file can be downloaded as and when required for storage on the external magneto-optical disc simply by repeating the download operation an appropriate number of times. However, if the main microprocessor is required to carry out all the above operations, then when the microprocessor is controlling the disc, the unit itself will be prevented from receiving data from the host computer. In this case download control must be exercised by programming the microprocessor to permit downloads only when the host computer has been advised by means of a handshake signal that a download operation is enabled and by inhibiting downloads at all other times. Unfortunately, a configuration of this type not only greatly prolongs the required transfer time and the costs of transfer but also limits the host computer's parallel processing capacity. If we are to exercise effective control over karaoke music reproduction time, then clearly we must find the answers to these problems.
The procedure adopted for the reproduction of music by driving a sound source conforming to the MIDI standard, is first to process data serially in a sequencer and then to transmit the processed data to the sound source. In terms of the control operations involved, "n" bits of music data must first be output in parallel from the main microprocessor and stored in the sequencer buffer. A start bit and a stop must then be added to the "n" data bits in the buffer and the processed "n+2" data bits transmitted serially via the I/O port to the sound source. The serial data is then analyzed by the microprocessor incorporated into the sound source in order to generate analog audio signals which are subsequently output from the sound source to an amplifier. This type of control, however, necessitates the conversion to a serial data format of the "n" musical data bits output in parallel from the microprocessor to the sequencer output buffer, which makes the required processing time considerably longer than would be the case if the data could be left in a parallel format for retransmission from the sequencer buffer. Furthermore, while data is being output serially to the sound source, receipt of the next musical data frame from the main microprocessor by the sequencer output buffer is inhibited. In other words, the wait time required for data input in parallel to the sequencer is dictated by the length of time taken for the serial output of data from the sequencer. Furthermore, a start bit and a stop bit must also be added to mark the beginning and end of an input data frame consisting of "n" data bits thereby increasing the length of the output data frame to "N+2" musical data bits. This increases the difference between input and output time yet further and in so doing creates a substantial obstacle to the achievement of precise time control which is one of the principal prerequisites for the successful performance of music. An additional problem is that even if a situation occurs wherein the sound source is still in course of processing data internally and is not yet able to receive the next data frame from the sequencer, there is no signal line defined for the purpose of advising the sequencer to suspend transmission of the next input frame to the sound source until such time as it has completed its current processing operation. The sound source is thus unable to control the operations of other peripheral units with the result that the data overflows and the reproduction becomes defective. If we are to exercise effective control over reproduction time, then clearly we must also find the answers to these problems.
The successful reproduction of a piece of music through the medium of a sound source requires not only the accurate reproduction of the volume, tone and power of the piece but also a faithful representation of the tempo of the music. In the case of a piece of music with a constant tempo, the tempo related information need only be input once at the start of reproduction. However, the effectiveness of a musical performance can be greatly enhanced by the inclusion of variations played at different tempos, for example, or by the incorporation of a gradual slowing of tempo (ritardando) towards the end of the piece, and these effects must be accurately reflected in the reproduction. The time control and processing of the corresponding stream of binary coded data bits naturally requires special configuration. If, however, the amount of data relating to a given piece of music is ambitiously augmented for the sake of enhancing the musicality of the reproduction, then this will effectively reduce the capacity of the main microprocessor to handle other processing operations, and is thus a situation which must be avoided. A method is, therefore, called for which will enable enhancement of the musicality of a reproduction while at the same time keeping any increase in the amount of required data within acceptable limits.
The way in which a network is configured around a host computer and digitally coded music signals are transmitted to a number of terminal units, which falls into the same sort of technical field as the present invention, is already known insofar as it involves no more than the use of digital music signals in a computer network. A typical system of this type might, for example, be configured in such a way that digital signals could be transmitted from a host computer database to a personal computer, which would function as the terminal unit. A programmable sound generator IC incorporated into the said terminal unit would then analyze the music for reproduction in accordance with the language recorded on the IC. The type of IC used here can be produced quite cheaply which means that the cost of the terminal unit can also be kept down. On the other hand, however, this type of IC has only limited capacity and is not capable of sophisticated multiple sound level control. In these respects, therefore, the way in which this IC solves the problems posed above differs from the technical solutions proposed by the applicants in respect of the present invention.